Determining Interwell Connectivity and Reservoir Complexity through Frac Pressure Hits and Production Interference Analysis

Abstract

This paper presents a process for analyzing production interference and interwell hydraulic fracturing pressure hits for multi-well horizontal pads in unconventional reservoirs. Ten wells with varied spacing in separate formations are evaluated. The analysis determines the degree of connectivity between the wells to help assess the extent and complexity of the stimulated network. Many of these connections persist through flowback and early production. The results of the study impact decisions regarding well spacing, injection rate, perforation design and frac order.A prescriptive completions program enabled observation of pressure interactions between wells during multi-stage hydraulic fracturing. Wellhead pressures are continuously recorded during all completions and flowback operations. The rate of pressure buildup plus the magnitude and frequency of the inter-well hits are studied. Pressure hits are then compared with production interactions between wells. Connections are mapped to form a comprehensive image of the fracture network.In the pad studied, all wells had multiple hits with varying degrees of communication across the fracture network. Observations confirm that fractures had significant vertical and lateral growth establishing a highly complex network. Interference analysis indicates the connections between wells often diminish over time. As a final validation, the high degree of interaction and fracture overlap are shown to be consistent with high-resolution microseismic observations.Establishing the extent of the effective fracture network is fundamental to deciding design variables. Multi-variable pad designs and production results can only be deciphered when viewed in conjunction with fracture interactions. The process discussed provides a simple way to observe and understand these interactions.

Strategies for Effective Stimulation of Multiple Perforation Clusters in Horizontal Wells

“…The model allows us to investigate problems such as the influence of cluster spacing and stage spacing on fracture propagation in multiple wells in a pad and fracturing of infill wells in a partially depleted reservoir. Example results are shown to illustrate how the model can be used to simulate complex pad-scale scenarios with multiple wells such as, zipper fracturing, frac wave (Sardinha et al 2014) and other innovative fracture sequencing strategies. Fracture closure is also automatically handled in the formulation.…”

A Validation Assessment of Microseismic Monitoring

“…No comparison was made with microseismic length at the time of intersection, but the microseismic data appear to be consistent with the fracture hits. Sardinha et al (2014) present a comprehensive study of fracture hits between 10 wells in a stacked sequence using pressure interference during the stimulations. The study also has microseismic data, but no correlation between fracture hits and microseismic length was made in the published study.…”

A Semi-Analytical Pressure-Transient Model to Detect Inter-well Interference of Multi-Well-Pad-Production Scheme in Shale Gas Reservoirs

“…Micro-seismic fracturing mapping shows hydraulic fractures extending between wells, gaining the existence of Inter-Well Pressure Interference (IWPI) (Farley and Hutchinson, 2014;Sardinha et al, 2014). Although recognizing IWPI within MWPP scheme can provide valuable insights to gain a better understanding of the fracture design (Soroush et al, 2013;Kaviani et al, 2010), enhancement of the possibilities of IWPI in MWPP scheme severely distorts flow regimes, which increases the burden of parameter estimations (Awada et al, 2015).…”